Floppy magnetic recording discs are flexible discs of polyester resin or the like having a magnetic layer on each side thereof on which information is recorded by a magnetic head. Floppy discs which have a diameter of 3 1/2 inches (8.9 cm) or less are known as micro-floppy discs. Generally, the micro-floppy disc is accommodated in a hard casing to form a cartridge. The micro-floppy disc comprises a circular magnetic recording medium which is thin, has a small diameter, and has a hub fixed to the center of the recording medium.
The cover and back shells of a typical micro-floppy disc cartridge are shown in FIGS. 1 and 2. As shown in FIG. 1, cover shell 10 has a recessed portion 12 which is configured to receive a shutter 14 having a window 15. When in the closed position, shutter 14 covers opening 16 in shell 10 which is designed to allow a disc drive to access a disc-shaped recording medium (not shown) within the cartridge. When shutter 14 is opened, window 15 in the shutter becomes aligned with opening 16 in shell 10, allowing a drive to read/write the medium.
As shown in FIG. 2, back shell 20 has a recessed portion 22 configured to receive shutter 14 having a window 25. When shutter 14 is opened, window 25 in the shutter is aligned with opening 26 in back shell 20. Unlike cover shell 10, back shell 20 has a central hole 28 for exposing the central hub of the disc-shaped medium (not shown).